Horror movies have sounds that we can’t quite assign names to. We all recognize them when they creep into the score, but can hardly describe them beyond “ominous creaking” or “reverb-heavy clang” or “wailing screech.” But it turns out that there exists a secret instrument, a diabolical machine capable of making the inhuman, haunting noises that set the mood and set the audience on edge. You know it, you’re afraid of it, and now you must learn its name: meet the fiendish contraption known as the Apprehension Engine.

In a newly posted video, film score composer Mark Korven shows off his demon baby, a one-of-a-kind noisemaker he’s affectionately dubbed The Apprehension Engine. Tired of the same old samples cropping up in movie after movie, the musician (whose credits include Vincenzo Natali’s Cube and, more recently, colonial-era chiller The Witch) wanted something he could use to produce original sound effects. He commissioned guitar maker Tony Duggan-Smith to create the nightmarish machine in the video above, which uses metal rulers, curled scrap metal, and other assorted bits of junk to generate supremely disturbing... music?

The video’s nifty enough, but its most interesting point lands near the end, where Korven wonders if what he’s doing technically qualifies as music. We may remember Jason Segel’s character in Forgetting Sarah Marshall unhappily squandering his skill as a musician on the droning score for a supernatural-thriller TV show, and his complaint that “It’s not even music! It’s just tones!” Korven respectfully begs to differ, figuring that if what he does is a series of deliberate noises designed to evoke feeling through non-verbal sound, what’s to stop him from calling that music? Steve Reich would most likely have his back on this one.

More From K-Fox 95.5